I am not an expert rider by any means however my 400ex nose dives every time I jump it. I started giving more throttle at the end of a jump and that helped but if it is muddy that doesn't work. Am I doing something wrong or is the preload on the stock rear shock need adjusted. And if this is it, how does one go about setting the preload on a rear shock.

 

lean back more

 

Maybe you are chopping the throttle as you leave the jump? Try to just roll off the throttle instead. Also, make sure you are not accidentally tapping the rear brake.

 

If you are leaving the jump correctly and it is still nose diving you usually have a suspension problem. My guess is you need to slow down your rebound on your rear shock or stiffen your front shock up to match the rear. A lot of people forget the fact that if one shock is working difrent than the other it throws your bike screwy. But it could just be the way you jump if you dont have much time on the machine!

 

One thing is possibly the rebound is set too fast. Mine was set too fast for my weight 150lbs. so if you are lighter like me that might be a problem. Definitely you need to match up your suspension I would probably stiffen up your front shocks all the way. Especially if you are jumping alot.

My basic approach to jumping is to keep an even throttle all the way to lift off. Always be conscious of your throttle control as you launch. I almost always position myself toward the center or slightly rear of the bike.

Adam Smith

99 400EX

 

You're probably just letting off the gas too soon before you get airborne. Stay on the gas until you're rear tires are off the ground.

 

i do the same thing nose dive! sometimes it lands sideways. that really sucks. i think i might go back to a dirt bike. something about jumping a quad just aint right. to heavy. i weigh 215 plus the quad weight. thats almost 600 pounds flying through the air. a bike is much lighter an more controlable.

 

With a 4-stroke, you HAVE TO STAY ON THE GAS RIGHT OFF THE END OF THE JUMP. That means, you don't let off the throtle until your rear wheels have completely left the ground!! Just yesterday, I saw a beginner who didn't understand this principle nearly get a face full of sand! You can also "panic rev" the engine in the air (the torque of the spinning wheels will help hold the front up), but many say this is hard on 4-stroke engines. If your nose pitches to high, you can correct by taping the (rear!) brake (has the opposite effect of a pannic rev). Of course, on small jumps you won't have enough "hang time" to do any corrections, so you need to get it right, right off the ramp.

Some people try to aproach the jump ramp at high speed, and count on their momentum to carry them over. This works with a 2-stroke, where you can blip the throtle as you hit the ramp (this is what all those guys on 250Rs are doing in those videos), but is a mistake on a 4-stroke. On a 4-stroke, I aproach the ramp at only moderate speed, then pin the throtle at the bottom of the ramp, and wheelie off the end of the ramp. I stay in a fairly low gear (3rd, or even 2nd on little stuff), because torque is your friend here! This can give you better height even off small jumps, and thus more hang time.

There is a great article on shock adjustment. I'll post it as soon as I can find the address.

 

It sounds like you might need to set your rear sag (1/3 of the total travel), you may want to go a lower if your light. You should be able to go off a smooth faced jump (with a steady throtle) and land flat.

I'm 34yrs old at 220+ lbs. and I can't my 400EX on the ground. I built a 3/4 Mile MX track in my yard with a 85ft stepup, two 45ft doubles and about twenty other obstials.

 

To set the sag first messure to a piont on the sub frame when the shock is fully extened (pick up on the grab bar untell the rear tires are just about to come off the ground)down to the top of the axel. Then sit on the bike in your normal riding position and messure again, it should be about three and a 1/4 inches or 1/3 of the total travel, below the first messurement. That is just a good place to start, you can adjust it depending on rider weight and track conditions.